1. Field of the Invention
The present invention relates to semiconductor devices and, more particularly, to a semiconductor device such as a chip module, which is formed by mounting a semiconductor chip onto a built-up substrate.
2. Description of the Related Art
Conventionally, a single-chip module or a multi-chip module is generally formed by mounting a semiconductor chip or a plurality of semiconductor chips onto a multi-layer substrate (also refereed to as a laminated circuit board) such as a built-up substrate. The built-up substrate can be manufactured, for example, by laminating circuit-pattern layers on both sides of a core substrate (for example, refer to Patent Document 1 and Patent Document 2). A chip module is manufactured by preparing such a built-up substrate and mounting one or a plurality of semiconductor chips and peripheral electronic parts onto the prepared built-up substrate.
In the manufacturing process of such a chip module, it is general that a process of preparing a built-up substrate and a process of mounting a semiconductor chip are separate processes. Here, an example of a manufacturing process of a conventional chip module is shown in FIG. 1.
In the manufacturing process shown in FIG. 1, a built-up substrate 1 having wirings formed therein and a surface on which electrodes for connecting a semiconductor chip and electronic parts such as passive elements are formed (FIG. 1-(a)). Then, a semiconductor chip 2 is mounted on the prepared built-up substrate 1 (FIG. 1-b)). In the example shown in FIG. 1, semiconductor chips 2 having solder bumps are flip-chip mounted onto one side of the built-up substrate 1, and the solder bumps are melted by a reflow process. After mounting the semiconductor chips 2 onto the built-up substrate 1, chip parts 3 such as capacitors are mounted onto a backside of the built-up substrate 1 (FIG. 1-(c)). Also in this process, the chip parts 3 are mounted by reflowing solder. Then, an under-fill 4 is filled between each of the mounted semiconductor chips 2 and the built-up substrate 1 and the under fill 4 is cured by heating so as to fix the semiconductor chips 2 onto the built-up substrate 1 (FIG. 1-(d)). After curing the under-fill 4, a heat spreader 5 is mounted onto a backside of each of the semiconductor chips 2 via an adhesive and the adhesive is cured by heating so as to fix the heat spreader 5 onto each of the semiconductor chips 2 (FIG. 1-(e)).
In the above-mentioned manufacturing process, a manufacturer of the built-up substrate 1 usually differs from a manufacturer of the chip module in many cases. That is, in many cases, the built-up substrate 1 manufactured by the process of FIG. 1-(a) is conveyed to another place after being manufactured so as to be supplied to the process of FIG. 1-(b). Moreover, although the manufacturing process shown in FIG. 1-(b) through FIG. 1-(e) includes heating processes such as a heat-curing process of the under-fill 4 and a heat-curing process of the adhesive, the heating processes are separate processes from each other.
As mentioned above, many processes are included in the manufacturing process of the conventional chip module as shown in FIG. 1.
On the other hand, there is suggested a technique to form a chip module by embedding a semiconductor chip into a built-up substrate (for example, refer to Patent Document 3 and Patent Document 4). In order to embed a semiconductor chip into a built-up substrate, a process of mounting a semiconductor chip onto a substrate must be contained in a manufacturing process of the built-up substrate.    Patent Document 1: Japanese Laid-Open Patent Application No. 2005-340686    Patent Document 2: Japanese Laid-Open Patent Application No. 2005-340687    Patent Document 3: Japanese Laid-Open Patent Application No. 2000-223837    Patent Document 4: Japanese Laid-Open Patent Application No. 8-316641
As mentioned above, there is a method of manufacturing a chip module in which, after manufacturing a built-up substrate, a semiconductor chip is mounted onto the built-up substrate in a separate process. In this method, the substrate-manufacturing process and the chip-mounting process are separate processes, and, thus, there is a problem in that a number of processes to finally complete a chip module is large and it takes a time to complete the chip module.
On the other hand, the mounting process of a semiconductor chip can be included in the substrate manufacturing process by embedding the semiconductor chip in a built-up substrate. However, if the semiconductor chip is embedded in a built-up substrate, heat radiation from the semiconductor chip is restricted since the semiconductor chip is covered by an insulating layer and an adhesive layer of the substrate. Additionally, even if a hat spreader for cooling the semiconductor chip is provided, the heat spreader itself is embedded in the substrate, which prevents the semiconductor chip from radiating heat. Therefore, it is difficult to embed a semiconductor chip generating a large amount of heat such as a CPU, and the semiconductor chip embedded in the substrate is limited to a relatively small-size semiconductor chip generating a small amount of heat.